The outfit was afaik a disappointment in sales and kinda regarded by critics as a underrated game in terms of sales. Vgcharts says that the game sold 220 000 copies, which is pretty bad.
Wh40k games are popular because of the license and what Relic did with it. OFC a license will sell x amount of games because of earlier fan following and brand recognition, but with the amount of expansions and a sequel that Dawn of war got, I'd guess it sold at least decently.
![:) :)](/images/Smileys/smile.gif)
I read once on relicnews were someone claimed that Dawn of War 1 sold 1.5 million (comment was 06) but he didn't provide any source.